Mail server replacement

The last exim3 MTA (whittlesey) is about to be replaced by an exim4 one (sutton). This should not cause any disruption, but please email sys-admin if you suspect any problems. If email is completely failing, do phone or come to see us.
Shutting down the last exim 3 server allows us to drop legacy features, and when we are convinced we won’t need to roll back to either of the old exim3 servers, we’ll be in a position to make use of new facilities in exim4.